I would suggest you go to
www.hp.com
- click on:
> Support & Drivers
> HP Support for your product
> Home PCs
Enter your product number (HP Pavilion 6540c) in the input box and hit enter
- click on:
> Drivers and Downloads
> Windows 2000 professional link
Or follow this link if it works:
http://h20015.www2.hp.com/en/document.jhtml?lc=en&docName=bph05537&prodId=hppavilion18818&lc=en
Here you will find pretty much ALL the info you need about upgrading your PCs OS. The article is titled "HP Pavilion Desktop PCs - Upgrading from Windows 98 to Windows 2000"
Regarding hardware and drivers, I would suggest finding out exactly what all your hardware is, (motherboard, video card, soundcard,...etc. If you have following the above links, you should be browsing links associated with your exact model) then visit each manufacturer's site for the latest firmware and drivers. I would think after doing so, You should then be able to run Win2000 no problem. (But there is really only one way to know for sure... You canalways run the HP restore process if you run into too many problems)
Good Luck!